House Republican Leader Tom Cross is moving to halt a perk that has allowed Chicago union leaders to reap inflated retirement benefits from ailing city pension funds.

The proposed legislation is in response to a Tribune/WGN-TV investigation that found at least 23 labor leaders stand to collect approximately $56 million from two city pensions funds over their lifetimes.

The investigation showed how a 1991 law permits union leaders who have taken leaves of absence from city work to tap into the city pension funds based on their union salaries. Those salaries are much higher than the city salaries, significantly boosting the pensions.

"At minimum, going forward you would no longer be able to do what they've been doing," Cross said Thursday before filing a bill that would alter the 1991 law. "To allow this to happen is crazy."

Previously, Senate President John Cullerton, a Democrat, acknowledged that the law now seems like a bad idea.

"Outliers such as those highlighted by the WGN and Tribune reports should be corrected in order to help restore the system's fiscal and public integrity," he said in a statement. "My hope would be that this could become part of the discussion during the upcoming fall session or the new session in January."

Mayor Rahm Emanuel declined to talk about such specific reforms Thursday. The mayor reframed the issue as a broader one involving a city pension system with runaway costs.

"If we're going to have the opportunity to fix something, I want to fix the problem, the overall problem, not the individual challenge that's set out," he said, responding to reporters' questions. "That would be a mistake for the taxpayers of the city of Chicago."

Emanuel's comments followed a Tribune/WGN report that described how Dennis Gannon, who eventually came to lead the Chicago Federation of Labor, was allowed to work for one day for the city to qualify for the pension perk. This and previous reports have shown how the once-healthy pension funds were raided and manipulated over the years for political gain.

The mayor focused on what he described as the larger issue.

"You say that, look, this is not about individuals. We have a systemwide problem in our state, and our city," he said. "At the end of the day, the taxpayers are on the hook, and I don't believe taxpayers should be left on the hook for a system that's not honest to them, and not honest to the people who are contributing to it. Now, one individual is not the problem."

On Thursday, Cross said he plans to move the legislation during the veto session, which starts at the end of October, and add additional provisions later.

He leads the minority party in the House, so it's unlikely he'll get traction on the pension changes without Democratic support. The fall session lasts only two weeks, making it difficult to get a bill passed that quickly. If Democrats decide to move ahead on the issue, action would more likely take place in the spring.

Cross said he has directed staff to examine whether they can make the changes for labor leaders who haven't retired from the city but have applied for the perk. That would directly challenge the idea that all accrued benefits are protected by the state constitution.

"We are in uncharted territory, and this would be a struggle," he said. "But we're going to see if we can go back and take away those benefits for those who haven't retired yet."

At the very least, Cross said, changes in the law could diminish benefits accrued after the effective date, meaning the labor leaders could hold on to pension money they had already built up but their pension would no longer be based on their union salaries.

He also said he would explore what the state can do to ensure that the pension laws are being enforced properly by the managers of the city funds. As part of the joint investigation, the Tribune and WGN-TV reported that some union leaders violated state law by collecting union pension credits on top of their inflated city pension for the same time period.

Those union officials were given a chance to renounce their union benefits and remain in the city funds. Yet, later, those same labor officials tried to tap that money through a different union pension plan, documents and interviews show.

"My office is looking to ensure that any violators of this provision are properly punished for their actions," Cross said.